Multiplex telegraphy.



R. A. FESSBNDBN.

MULTIPLBX TELEGRABHY. APPLICATION FILED JANA. 190a.

Patented Jan. 10, 1911. A

:NiTNESSESZ a tion.

.a-nd described herein, the currents received s'rrrrns rn'r-nn'r orricn. I

REGINALT) A. FESSENDEN, OF WASHINGTON, DISTRICT OF, COLUMBIA.

MULTIPLE)! TELEGRAPHY.

Specification of Letters Patent.

Application filed January 4, 1906. Serial No. 294,584.

To all whom "it may concern:

Be it known that I, REGINALD A. FnssnN- DEN, residing at \Vashington, District of Columbia, a citizen of the United States, have invented certain new and useful Improvements in lirlultiplex-Telegraphy, of which the following is a specification.

The invention described herein relates to the transmission of electrical energy, as in telegra hy, by alternating or fluctuating currents, t e improvement being especia ly applicable to multiplex telegraphy. .1

Among the many reasons pointed out y me, the failure to attain practical resu ts, seems to be due principally to the fact that over long transmission lines it'is not advisable to use a very high frequency, as the attenuation and distortion produced by capacity eflects of the line and other causes, are very great. Since resonance is dependent u on the cumulative effect of succeeding impu ses, a certain number of impulses must be received before the desired cumulative efi'ect or resonance is produced, and

this takes time. \Vhen using a frequency of two hundred and fifty per second, a strong resonant effect requiring the accumulative energy of one hundredimpulses cannot be produced in a sufliciently short time as with an ordinary high speed operator the time required for making a dot is one twenty-fifth (1/25) of a second or less, so thatwith two hundred and fifty cycles per second, only ten impulses would be received during the time of making a dot; hence, the selectivity would be poor and much less than that required. And further, leakage, capacity efi'ects, etc. produce such attenuation, that impulses received from a nearby station would be strong as compared with those from a distant station, and hence would overcome the resonant effect and disturb the signals.

My improved method consists generally stated in transmitting alternating or fluctuating currents of a certain frequency from a station, and in causing these currents u'hbn .received at another or receiving station, to

interact with'alternating or fluctuating currents flowing throu h a local circuit and preferably generated at the receiving sta- In the"""particular embodiment shown pass through a coil of an electromagnetic indicating mechanism having a local'mag-' Patented Jan. 10, @9111.

. netic field generated not by permanent or direct current electromagnets, or by the in-' coming current but by a current flowing in a. local circuit.

The invention is hereinafter described and claimed.

In the accompanying drawing, formin a part of this specification, I have shown d iamore fullygrammatically two stations with'circuits and apparatus included therein.

At station A, I employ an alternating current machine, 1, either driven directly by a prime mover, as a generator, or driven as.

shown, as a synchronous motor by a generator, At station B, I employ a synchronous alternating current motor, 3, having one of its terminals connected by a line wire, 4, to a'terminal of the machine, 1, at station A. The other terminals of the electric machines, 1 and 3, may be grounded or connected by a return wire, as is well known in the art. These electric machines are operated synchronously, synchronlsm being obtained by connecting themto the same 211- ternating current generator, 2, as shown or otherwise as convenient. These electric machines control the current flowingin two circuits at. each station. This control may be etl'ected by operating two alternating current generators by the machiues,'-l and 3, or by operating two commutators, ,5, (5 and 7, 8, which are included in the circuits of batteries, S), 10 and 11, 12. The control effected by either of these means is such that when using alternating current generators, the

current in one circuit at A will have the a same alternations per second as those in one circuit at B, and the alternations in the other circuits at- A and B will be equal but diifen ent from the alternations of the first circuits.

When using batteries or direct current generators and commutators driven by the 7 machines. 1 and 3, the commutator-s are so constructed that 5 and 7 will produce the same number of breaks per second, or the frequency of one breakmay be a multipleof the frequency of the other. The commutator 6 will produce the same number of break as S, but the number of breaks produced b produced by 5 and 7. The circuits of the generators 9, 10, 11 and 12, may be entirely metallic or be formed in part by ound as shown, and these circuits incln e r tively fixed coils, 13, It, 15,145,; I It)? y 6 and 8 Willbe different from those,

of currents flowing through 13 and 15 are actuation isdetermined by cointhe same or'o multiple of each other and mutator, 5, will also flow through movable those of current flowing through 1% and 16 coil, 20, but since the current in its comare e some or a multiple of each other. panion ilted coil, 16, has a frequency or line Movable co1ls,l7.18,19 and 20 are mounted tuation dilferent from that of the'cuncnt o move by their torque smnlarl to in the motable coil, bein determined by the ndynamometer and arranged in operative commutator, 8, or its described equivalent relation to the fixed coils, 13, 14, 15, 16, and the torque between coils lb and '20 will be their individual circuits are connected to the alternating in direction and of a character 75 line wire, 4, and to ground or a return wile known in the physics of sounds as beats.

' either directl as shown in the case of coils 'l'hc disturbing ell'ect of these beats can be 18 and 20, or through a capacity, 21, and an done away wit 1 in several ways. When the inductance, 22, placed in series with each movable coils are employed to actuate a'telother as in the case of coil 1? shown at stacphone diaphragm, the neutralization of the tion A. Either the capacity or the induceli'ects of beats is urmecessary, as the beats, Lance may LIE used alone, depending upon which can be controlled by properly pro natural constants of the circuit; that is, if portioning the trequencies,*will have such a there is'already sutticient capacity in the cir different frequency as not tosinterfere with cult, the capacity 21 need. not be used.- lC perception of the sound signals. In the lnductances, 23, may be placed in series apparatus shown, the inertia of the coils with the tired coils as shown in the case of themselves and the relay contacts or sounder coils 13and 15,. inc a capacity, 24 which lingers, 26, is such that by adjusting the fremay be variable, is placed in series with the qucncies so that the beat "requency will be movable coil, as shown in the case of 19; and ugh, 2'. c. more than twenty-five times a an inductance, 25, may be placed in series second, the movable coils will be incapable a so as in the ease of coil 17. of responding to the beat frequencies, but

The movable coils may operate as sound- Wi c responsive to the slower impulses ers they being provided with ngers, 26, caused by closing the key, 3 Fol-the reaand springs, 2?, or as shown in ca e of COIl sons stated, nomdication will be produced I 8 it may operate to control a local circuit by the How of a portiomof the current from including a sounder, 28 and a generator, 29. the line wire through the movable coil, 20. Telegraph keys are shown at 31, 32, 33 i /hen the key, 31, is closed, two currentsand 3%. will flow through thecoil, 17, one with the When all the keys are o.en, cu'rrents'of frequency of the sync. ionizing generator, 2, lot one frequency or number of uctuations oer while the other current will have a different second will flow through coils l3 and 15, and frequency, dete mined bythe commutator, currents of a different frequency or rate of 5, or its described e uivalent. Both ourfluctuations will flow through coils l4 and rents, unless rendered inoperative, would 16. s the movable coils are normally arproduce an indication. he synclmmizing 10'5 ran ed at right angles to, the tired coils, they frequency may be eliminated byv means of will not ac as secondaries oftransformcrs the capacity, 21, and inductance, 22, or the and no current will flow tirough them currents in the fixed coil, 13, and movable Should any secondary action exist it may coil, 1 may be so'displaced in phase by be overcome by methods well known, as a means of the inductance, 22, and ca'pacity, r ative; osition can-alwaysbe found where 21, or the inductance, 23, or capacity, 30, there wil not e anymutual induction be that no indication will be produced. The tween the fixed and movable coils, or one effect produced on the coils, l3 and 17, by- Where the mutual induction Wlll be so small the current having the frequency determined that there will not be any appreciable torque y the commutator, 5, may be entirel neu 1.15 between the movable and fixed coils. tralized by changing the phases of the'cur j hen key 31 at the station A is depressed, rents. It is preferred, however, not to encurrents of a' frequency or fluctuation, detirely neutralize this etl'ect, but to so adjust termined by commutator 5, or its described the phases that there will be a certain torque, equivalent, will flow on intoline, 4, and to permit the operator sending with the key, 12 through the movable coil, 19, at station B 31, to hear tie signals e is 'sending. The and since the current throughthe local fixe e ects 01 the twocurrents on the coils, 13 and coil, 15, has the; same frequency or fluctua- 1 7, may be neutralized if desired by the tion, as coil. 19, determined bythe commu spring, 27-, ut, as before stated it is )re tutor, or its described equivalent, there 'ferred to only partially neutralize the effect will be such a torque between t e coils, 15 of the sen inf; impulses. and 19, as willcause the C011, 19, to move Iii-while the operator at 31 is sending, and. produce an indication directl as b tie operator at station 13 should also send, moving a telephone d'iaphra m 26, or otherit is evident that the effect of the impulses wise; or it may-operate by closing a local sing key, 33, would be. weak- 7.30

esnaoe observed. that the fre sent out on 010 'those skilled in the art.

bodiment' of my invention,

connected by wire,

cued on account of the aforesaid difi'erence ated as to give currents of the same frequency, but displaced in phase and preferably at an angle of ninety degrees, so that the impulses sent out from B will when passing throu h the coil, 17, be in phase with the currents owin through thefixed coil, 3. That is since tEe commutator at B gem crates a voltage displaced-90 erated at A, as described, the currents, mm B are displaced 90additional, and the currents in coils 17 and 13 will be either together or 180 apart; that is they will be in phase so far as their mutual torque is concerned. If desired, the phase displacement may vary from ninety degrees and may be such that. impulses sent out from B will move the coil, 17, in one direction, while the impulses caused by closing key, 31, will cause the. coil, 17, to move in the opposite direction; With either of these arrangements or adjustments, the operator at B is able to break the operator at A: if he should desire to do so. i

With reference totcoils 14 and 18, the dis turbingefi'ect of impulses sent from B on closing key, 33,.is neutralized as described in the case of coils 16 and 20, when key 31 is closed. Eflfects-produced on 14 and 18 currents from the synchronizing generator, 2, and from. the commutator, 5, or its equivalent, when key 31 is closed, are neutralized in any of the ways described in connection with coils'13 and 1'7. To summarize, the coils, 14, 18' and 16, 20, are not affected when either or both of the and 33, are closed. Coils 15, 19 are afi'ectetl byclosing key, 31. The coils, 13, 17, are either not afl'ected'hy coil, 17, moves in a directlon opposite that produced by closing with a certain desired force.

hile I have described a particular em- I do not limit myself as regards the broad terms of the claims to such specific form, as many changes and modificationsflvithin the spirit of my invention will readily suggest themselves to Sending and receiving apparatus may be stations, as shown. It wi l be readily understood hy those skilled in the art, that resonance-effects can be used if desired. i

I claim herein as my invention: 1. In signaling apparatus, the combination of a transmitting and a receiving station means for sendingpcriodic impulses over thewire, devices at the sending station for controlling the emission of impulses to make signals, devices at the receivlng station for continuously locally sending station, means to create fields of force by from that en the transmitted impulses,

keys, 31

closing key, 31, or else,

key, 33, or else moves distributed at va- 'rious points along a line or localized at two generating impulses having a periodicity the same as, and in constant phase relation to, that of the transmitted impulses from the r the locally generated and the transmitted impulses respectively and means to produce an indication by said interaction of said fields of force.

2. In signalin apparatus, the combination with a sending and receiving station connected by wire, of means at the sending station for transmittin periodic impulses and devices for COIitlolfing the emission of the same to make signals, a local generator at the receiving station for continuously generating impulses of a periodicity similar to and in constant phase relation to, that of, means including two interacting and relatively movable coils generating interacting fields of force, one coil bein excited by the transmitted im-' pulses and the other by the locally generated 1mpulses,-and means to make a si nal operated by said interaction of said fields of force.

3. In signaling apparatus, the combination of a transmitting and a receiving station connected b wire, means for sending periodic i'mpu ses over the wire, devices at the sending station for controlling the emission of impulses to make signals, devices at the receiving station for continuously generating loca impulses having a )eriodicity similar to that of the transmitte impulses from the sending station, means to create interacting fields of forc e by the locally generated and the transmitted impulses respectively and means to produce anindication by said interaction of said fields of force, and means for maintainingthe local generator at the receiving station in synchronism with, and in constant phase relationto, the transmitting generator.

4. In signaling apparatus, the combination with-a sending and receiving station connected by wire, of a plurality of generators at the sending station adapted for transmitting periodic impulses of differentfrequencies, means at the receivingstation for continuously generating a plurality of sets of impulses of frequencies similar to those transmitted from the sending'station, means creating four or more interacting fields of force excited by the transmitted and local impulses of similar frequencies interacting on each other, and indicators operated bythe interaction of said pairs of fields of force.

5. In signalin apparatus, the conibina tion with a sent ing and receiving station connected by wire.

of a plurality of generstation adapted for ators at the sending interacting transmitting periodic impulses of different frequencies, means at the receiving station for continuously generating a plurality of in icators of said 021' each other, and the znteractlon fieldspf-force, a'nd"means for mamtaining the palrs of generators of impulses of simiin periodicity respectively in synchrom'sm 19 with each other.

In Witness whereof, I have hereunto set my hand.

REGINALD A. FESSENDEN- W itnesss: I

JESSIE E. BENT, ,DORQTHY. V. THURMAN. 

